In message <[EMAIL PROTECTED]>, Randy Bush writes:
>>> The proposed new words for 2460 effectively say
>>> - you don't have to set it
>>> - you don't have to look at it
>>> - you mustn't change it
>>> I don't think encourages kludge significantly more than MBZ text, but it
>>> does allow for future usage.
>> as I see it, the proposed words let us get Flow Label off our
>> plates for now, which is good because we don't know what to do
>> with it anyway. maybe someday someone wall make a convincing
>> case for how to use it.
>
>and, if we do mbz, they can then write the rfc which changes that
The problem then is all the implementations -- or firewalls -- that
will check that the bits really are zero upon receipt. If you want
MBZ, say "sender MUST set to zero; receiver and middle boxes MUST NOT
check".
Then you have to hope that folks listen to that part. Especially for
firewalls, I wouldn't count on that. (For precedent, so to speak, look
at what happened with the ECN bits when a particular version of Linux
started using them.)
--Steve Bellovin, http://www.research.att.com/~smb
Full text of "Firewalls" book now at http://www.wilyhacker.com
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